The Noh Mask Effect: A Facial Expression Illusion

The full-face masks worn by
skilled actors in Japanese Noh drama can induce a variety of perceived
expressions with changes in head orientation. Rotation of the head out
of the visual plane changes the two dimensional image characteristics
of the mask which viewers may misinterpret as non-rigid changes due
facial muscle action. The figure below shows the same Edo-period
Noh mask, Magojiro, at three inclinations.

The lifelike changeability of Noh masks has been known in Japanese theatre
for centuries. The earliest such Noh masks were carved in the Kamakura
period (1192 - 1333). The effect is considered to be an important ingredient
in the mysterious atmosphere of Noh drama.

Understanding the Noh Mask Effect

Examination of the the 3-D shape of the Noh mask suggests the origin
of this effect. The shape of the Noh mask exaggerates certain features,
particularly the depth of the contours of the mouth. The figure
below shows that the 2-D projection of these contours varies greatly
when the mask tilt is changed.

In the above figure, the 3-D shape of a Noh mask (Ko-omote) was
obtained using a Cyberware laser range scanner. In figure 2A,
the contour of the
upper lip has been highlighted to draw attention to the effect
of mouth inclination on its perceived shape. Other regions of the
mask such as the eye contours and brow paints undergo changes
in apparent shape as the mask is rotated forwards. In figure 2B,
the 3D shapes of a Noh mask and a Japanese womens face are shown for
comparison.

The unusual shape of the Noh mask is also apparent in the following
picture of a Magojiro Noh mask carved in the present era by a master
carver.

The animation below shows an animation of a Noh mask being rotated
about the horizontal axis.

The Noh mask effect seems to be lessened by this regular, predictable motion.

Related Publications

The following papers report joint cross-cultural
research on the Noh mask illusion
with Professor Ruth Campbell's
group
in the Department of Human Communication Science,
University College London. Our research showed strongly significant
cultural differences between Japanese and British subjects viewing the
Noh mask. The cultural effect did not extend to perception of facial
expressions of the
human face.

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